Gentle start with removing explicit interfaces

runtime/vm/snapshot_ids.h

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef VM_SNAPSHOT_IDS_H_
 #define VM_SNAPSHOT_IDS_H_
 
 #include "vm/raw_object.h"
 
 namespace dart {
 
 // Index for predefined singleton objects used in a snapshot.
 enum {
   kNullObject = 0,
   kSentinelObject,
   kEmptyArrayObject,
   kTrueValue,
   kFalseValue,
   kClassIdsOffset = kFalseValue,
 
   // The class ids of predefined classes are included in this list
   // at an offset of kClassIdsOffset.
 
   kObjectType = (kNumPredefinedCids + kClassIdsOffset),
   kNullType,
   kDynamicType,
   kVoidType,
-  kFunctionInterface,
-  kNumberInterface,
+  kFunctionType,
+  kNumberType,
   kDoubleInterface,
   kIntInterface,
   kBoolInterface,
   kStringInterface,
   kListInterface,
   kByteArrayInterface,
 
   kInstanceObjectId,
   kMaxPredefinedObjectIds,
   kInvalidIndex = -1,
 };
 
 }  // namespace dart
 
 #endif  // VM_SNAPSHOT_IDS_H_